A memory gremlin is a creature that feeds off other creatures and their memories. It can read people's memories and take the form of anything based on those memories. Usually a memory gremlin will assume a form that will help lure their target to its death. Being tricked into having sex with a memory gremlin is considered pretty embarrassing, as in their natural state, a memory gremlin has no orifices. In Foon, cheating on someone with a memory gremlin will generally end a relationship.

After a memory gremlin feeds off a person's energy, it will leave a very large hole in their mind that can be exploited by other psychic creatures.

The Memory Gremlin was asked back to the podcast after Usidore died to imitate him. She is now reformed, and is a vegan and eats only veeg (the stuff between grass and dirt).

Her actual name is Fi’ang Yalok (Fangy Ellie for short), the same as one of Usidore's name. There is an annual conference in Foon of all four beings with that name; the other two are a horse, and a wish that the horse made.